XML Paper Specification (XPS) Document

XPS Document is an electronic document format similar like PDF, it provides a single, high-fidelity document solution that supports multiple uses.

Typical uses for XPS document include desktop publishing, word processing, and form layout. The page layout remains the same in all cases, while the document quality maximized to the capabilities of each device.
Benefit from XPS Document:

Reading, writing and storing XPS Document content and resources as a single, portable, and easy-to-distribute file. You can use Microsoft XPS Document Writer to creating an XPS document, and this XPS Document Writer already installed on Windows Vista and Windows 7. For WinXP and Win2003 users the Microsoft XPS Document Writer is available after installing .NET Framework 3.0.

Displaying documents with an XPS Viewer.

Support security features, such digital signatures, to provide greater document security. When applied to a document, these digital signatures can help ensure the identity of the author and the validity of the document content.

You can adding personal comments and highlight on it (need XPS Annotator installed).